Material moving pumps, whether for moving liquids, solids or liquid entrained discrete solid material, or other product, for example manure, straw, crushed animal bones, sawdust, or feathers, typically include a ram that reciprocates in a pumping chamber undergoing a working stroke or power stroke during which material is moved through the chamber, and a return stroke whereby the ram returns to its starting position and more material is introduced into the chamber ahead of it. The ram is driven by a hydraulic motor of the cylinder-piston variety with the cylinder mounted in stationary relationship to and outside of the pumping chamber. The piston-rod is attached to the ram and reciprocates in the chamber. For example, see U.S. Pat. No. 4,322,023 to Olson issued Mar. 30, 1982 entitled Material Moving Apparatus. Such pumps are satisfactory for the pumping of most materials. However certain materials require a high degree of sanitation when being handled, such as food or food ingredients, or substances used in the manufacture of drugs and chemical products where purity is important. The presence of a piston shaft that reciprocates in and out of a cylinder can contaminate the environment of the pumping chamber, rendering the use of such pumps undesirable for handling these materials.